Heat treatment Elimination in Forged steel Crankshaft of Two-stage Compressor

Abstract

There are various components in reciprocating compressor; however, optimization of compressor crankshaft for design and manufacturing is planned by considering its volume and cost. The crankshaft used in this study is forged steel from a two-stage air compressor models. This is a single throw crankshaft consists of one drive end shaft (fly end), one non-drive end shaft (free end) and a crank pin. High strength, ductility, and fatigue resistance are critical properties required from the crankshaft material and manufacturing process. In spite of its generally lower fatigue resistance, ductile cast iron is a major competition to forged steel crankshafts in the competitor’s compressors. Moreover, there is no heat treatment process involved in case of ductile cast iron. Since a crankshaft experiences a large number of load cycles during its service life, fatigue performance and durability of this component is a key consideration in its design and performance evaluation. The design and manufacturing including heat treatment process of forged steel crankshaft is studied for optimization and to reduce cost.Experimental investigations made to evaluate the mechanical properties of the crankshaft material with and without heat treatment and compared. Design verification made through static and dynamic analysis using finite element software to find the factor of safety for both cases. Crankshafts are manufactured and it is assembled in the compressors and validation is done through accelerated tested at in-house as well as in the field to prove the process. The cost benefit analysis is done for manufacturing of the crankshaft without heat treatment.